Fellowship-CS011101 Graham Associates, Inc. i.c,
CONSULTING ENGINEERS & PLANNERS '
November 1, 2001 ~./0~O ~"0
C
City of Gr~v~e
P.O. Boxy5104
Grapev~e, Texas 76099
~:// Fellowship L~es
Cky of Grapev~e Co--ems
De~ ~. Dyer:
The follow~g is a respo~e to yo~ co~ents dated October 22, 2001 received p~su~t to yo~
review of our co~tmction docments for the a~ve referenced project.
1. O~ pro~sed ~provements do not ~ect the floodph~ elevation upstrem or
domtrem of the client's prope~y. ~e 0.01 foot dsc demo~trated ~ the ult~ate
condkion model occ~s o~y on o~ client's prope~y. It is o~ op~on that the ~tent of
the Cky of Coppell Ordnance, designat~g no ~crease ~ floodpla~ elevation, w~
~i~en to limk development ~t~ the floodpla~ of prope~ omers who do not om
~th sides of the c~el. Our c~ent om ~th sides of the chapel where the ~crease
occ~s ~d therefore should be allowed to modi~ the conditio~ as long as no change
occ~s up,rem or do~trem. Please reco~ider tbs issue.
2. HEC-2 models for the pro~sed ~d exist~g 10, 50, 100, ~d 500 ye~ sto~ events ~e
a~ached ~ requested.
3. The trail cross~g the ~ ~let to L~e No. 1 Mll co,om to the approved chapel
section for th~ c~el. There will be no reduction ~ conveyance. ~mo~g will occ~
at the ~et to the l~e ~ shorn on the pla~.
4. We considered both of the suggested spillway locmio~. Locating the spillway on the
domtrem eM of the dam would ~pact a ~t~e build~g aM p~k~g ~ea ~ well ~
requke addkioml tree removal. Locat~g the spillway ~ the middle of the dam would:
1)requke a costly concrete ~mct~e t~t w~ ~deskable to o~ c~ent; 2)create erosive
flows over a fill stmct~e that would requke com~u~g ~temnce; ~d 3)would create
a hydrau~c jump ~ lower flow condition; 4)~pact ~y matte trees ~ that ~ea. The
c~ent location w~ chosen to: a) ~m~e ~pact' to the exist~g trees; b) reduce
co~tmction cost; c) ~~e ~pact to the floodpla~; d) provide for e~e of t~ition
to the Co~onwood Brach when cha~el~tion occ~s at a later date; e) reduce the
elevation difference between the spillway crest ~d Co~onwood Brach chapel;
F:~ C~in~LWS~lo~hip Chumh ~e~ ~.d~
Summit Office P~rk Ce~terpoi~t Two B~k O~e
] 300 Summit Ave., Suite ~ 9 6] 6 Six Flags Drive, Suite 400 ] ] ] S. G~rlond Ave., Suite 202
Ft. Womb, Texos 76] 02 Arlin~on, Texos 7601 ] G~rlond, Xex~s 75040
[8] 7} 332-5756 (gl 7} 6~9-8530 · Metro {817) 640-8535 {972} 272-4655
F~ [81 7} 336-6909 F~ [817} 633-5240 F~ [972} 272-4655
f)allow for convergence of flow. We prefer to leave the spillway where we have it
located. Armoring has been provided where erosive velocities and flows occur in the
spillway and discharge channel. The side slopes of 4' to 1' along the discharge channel
allow for mowing, ease of maintenance, and reduces the area impacted by the
construction of the facility.
5. Enclosed please f'md a copy of F.I.R.M. Panel Numbers 48113C 0135J dated 8/23/01,
which shows the existing floodplain and floodway. The enclosed "Hydraulic Work Map"
shows the ultimate condition floodway and floodplain.
6. From our site surveys and field investigation, we conclude the only wetland and/or waters
of the United States are in the bottom of Cottonwood Branch itself. The proposed
construction does not impact wetlands or waters of the United States. Therefore we are
in compliance with Section 404 of the Clean Water Act and Section 10 of the Rivers.and
Harbours Act of 1899. No Corp Permit will be required for this construCtion.
7. Sheet 7 of 11, "Storm Water Pollution Prevention Plan" demonstrates the proposed spoil
sites. Please see a copy of this plan sheet attached. All excess excavated earth will be
placed on the owners property in locations that minimize impact of the existing trees.
Tree mitigation is in progress.
8. We will begin the platting process and have it completed by the time construction is
completed.
We hope these responses satisfy your comments. Should you have any additional comments or
questions, or require additional information please do not hesitate to contact us.
Sincerely,
cc: Ken Griffin, P.E. - City of Coppell
F:~t.as C otina~FLW SHIP~ ellowship Church Lake'~h:o~ Dyer.doc